Multibody system dynamics analysis for valve trains

The theory of multibody system dynamics is used to simulate valve trains' kinematic and dynamic characteristics, and the methods of establishing and analyzing the multibody system dynamic model for valve trains are discussed. Since most of the flexible bodies of a valve train are slender parts, the finite segment method is used to build their models. Other parts such as cams, valve heads etc., are built as rigid bodies. After applying the constraints, forces and motions, the establishing of the whole system is accomplished, and the Lagrange's multiplier method can be used to obtain its dynamic constitutive equations. As an example, a valve train's multibody system model of 4100QB engine, produced by the Yunnan Internal Combustion Engine Limited-Liability Company. is established. The analysis results obtained show that its working performance is generally good except that the air-pass ability and the lubrication effect of the cam and the tappet need to be improved.